So as everyone may know you can get a mp7 varriant early on. Can you unlock and work on the camos using the different variant of the mp7 even though the gun is locked?
Yes you will get the unlocks for it. Same with the default class weapons, even if you don't have the weapon unlocked you still level them up when you use them so when you do unlock them you will already have some attachments and camos. I noticed this when I first started playing and was running gunfight.